1. Field of the Invention
The present invention relates to a substrate requiring protrusions in the display area, such as in the case of a plasma display (PDP), and more specifically to a technology for manufacturing a substrate utilizing a transfer method using an intaglio plate for transfer.
2. Description of the Related Art
A PDP will be described as an example of a case where a substrate having protrusions according to the present invention is required. A PDP is a self light emitting display panel where a pair of substrates (normally glass substrates) are disposed facing each other with a small space in between, and a discharge space is created inside by sealing the periphery thereof.
Generally in a PDP, ribs (protrusions) with a 100 to 250 μm height to partition the discharge space, are formed on a substrate in a repeated manner. For example, in the case of a surface-discharge type PDP which is suitable for color display, ribs having a pattern which can be seen as stripes when the PDP is viewed directly, are formed on the substrate with equal spaces in between along the address electrode lines. By these ribs, discharge interference and cross-talk of colors are prevented.
As a general process to manufacture a PDP substrate having the above mentioned structure, the address electrode pattern is formed on the substrate, and the ribs are formed so as to align to the electrode pattern. Various methods have been proposed and used for forming the ribs, but typical methods are a multilayer printing method, sandblast method, additive method, photo-lithography method and transfer method, of which the transfer method, with which the lowest cost may be possible, has high expectations.
The transfer method is a method of forming the ribs or a method of simultaneously forming the ribs and a dielectric layer on a substrate, using an intaglio plate for transfer having grooves for forming ribs. As a procedure, a molding material is filled into the surface of the intaglio plate for transfer, then the solidified or cured molding material that has been filled is transferred to the substrate to form the ribs and the dielectric layer (e.g. Japanese Patent No. 3321129 (claims), Japanese Patent Application Laid-Open No. H8-273537 (claims), and Japanese Patent Application Laid-Open No. 2001-191345 (claims).
The transfer methods include an adhesion transfer method (see Japanese Patent Application Laid-Open No. H10-326560 (claims)) where a transfer material is solidified by removing the solvent of the transfer material filled in the grooves of an intaglio plate for transfer, and the transfer material is transferred to a substrate utilizing the adhesion of the transfer material, and an ultraviolet (UV)-curing transfer method (see Japanese Patent Application Laid-Open No. 2001-191345 (claims)), where an ultraviolet-curable transfer material is inserted between an intaglio plate for transfer and a substrate, the transfer material is extended by a roller or the like with the intaglio plate for transfer and the substrate pressing against each other, and is filled into the concave portions of the intaglio plate for transfer, then the transfer material is adhered to the substrate by irradiating UV rays.
In the adhesion transfer method, a transfer material paste is filled into the grooves of the intaglio plate for transfer, then the solvent is removed to solidify the transfer material, so a material of an intaglio plate for transfer with low hardness can be used, and when the intaglio plate for transfer is released (demolded), little damage occurs even if the shape of the ribs is complicated.